World Wide Web Consortium Releases First Working Drafts of XML Schema
Specification

W3C Members Collaborate to Improve and Standardize Needed Technology

http://www.w3.org/ -- 6 May, 1999 -- Leading the Web to
its full potential, the World Wide Web Consortium (W3C) today releases the
first public working drafts of the XML Schema specification:
XML Schema Part
1: Structuresand
XML Schema Part
2: Datatypes. By publishing these working drafts at an early stage
of the design work, W3C is ensuring that the public can follow the XML Schema
design work, and that the final result can be widely accepted and adopted.

One part proposes facilities for associating datatypes with
XML element types and attributes; this will allow
XML software to do a better job of managing dates, numbers, and other special
forms of information. The other part of the specification proposes methods
for describing the structure and constraining the contents of XML documents.
These drafts, which builds on
earlier work submitted
to W3C by several vendor and user organizations, are the first step in
the development of a powerful, vendor-neutral format for defining the rules
that govern particular kinds of XML data.

Following W3C's practice, the XML Schema Working Group provides a
public
mailing list for comments on the working drafts, in addition to the feedback
channels defined by the W3C Process. The address for comments is given in
the drafts themselves.

The Web needs Richer Data

Extensible Markup Language (XML) was originally
designed for encoding human-readable documents, but quickly attracted attention
from groups interested in electronic commerce, interchange of data from
relational and object-oriented databases, and other non-document applications.
The Resource Description Framework (RDF) was designed
to integrate a variety of web-based metadata activities including content
ratings, search engine data collection, and digital library collections.
Many applications can benefit from the development of schemas:

Databases must, for example, communicate detailed information about the legal
values of particular fields in the data being exchanged.

Publishing and syndication services must be able to describe the properties
of headlines, news stories, thumbnail images, cross-references, etc.

For electronic commerce, schemas can be used to define business transactions
within markets and between parties, and to provide rules for validating business
documents.

When XML is used to exchange technical information in a multi-vendor environment,
schemas will allow software to distinguish data governed by industry-standard
and vendor-specific schemas, and help applications know when it is safe to
ignore information they do not understand, and when they must not do so.
This means schemas may help make software more robust and systems more able
to change and adapt to evolving situations.

Traditional document processing will also benefit from XML Schemas, because
schema-aware document management systems will be better able to guide authors
and editors in the creation and maintenance of documents.

XML, in accordance with its origin, provides methods of expressing syntactic
validity constraints on document content, without attempting any formal
specification of the meaning of markup. RDF, starting from the problem of
describing Web resources in general, has focused more on the semantics of
metadata, and less on the syntax. One of the most important design challenges
for the ongoing work on XML Schemas and RDF is to ensure that their approaches
and data models converge.

What's new?

At present, rules about what kinds of information can appear in an XML document
can be expressed only in the form of XML document type definitions
(DTDs). DTDs use a special format to define the rules for using XML markup
for different kinds of documents, but in practice there are some common rules
that cannot be expressed at all in DTD form. XML Schemas are more powerful
than DTDs, so they will be able to express some rules that DTDs cannot express.

Even more important for many purposes is that XML schemas are themselves
XML documents. Using XML as the document format for schemas, instead of using
a special-purpose form as DTDs do, will allow users and developers of XML
schemas to use standard XML tools, the same ones they use for other structured
information, instead of having to shift to specialized tools for work on
schemas. It will also remove some of the shroud of mystery that have
traditionally made DTD development a black art. Any existing XML processor
can read an XML schema; interchange will be easy.

Cooperation Promotes Widespread Adoption

The XML Schema Working Group began its work by attempting to clarify the
scope of its work. Requirements and suggestions have been gathered and discussed;
eventually, these were refined into a short
requirements
document, which outlines some of the core usage scenarios and assumptions
that are governing the design of the XML Schema language.

The XML Schema work builds on existing W3C specifications and experience
in XML and database fields. The intense work of preparing these drafts has
harnessed the expertise of key players among the W3C Membership in the fields
of document management, database management, and electronic commerce. The
diversity of representation within the W3C working group helps ensure that
XML Schemas will be an open, vendor-neutral format that content creators
can easily use and depend upon for information interchange over the Web.
The purpose of these publications is to encourage public comments and
contributions.

About the World Wide Web Consortium [W3C]

The W3C was created to lead the Web to its full potential by developing common
protocols that promote its evolution and ensure its interoperability. It
is an international industry consortium jointly run by the
MIT Laboratory for Computer Science (MIT
LCS) in the USA, the National Institute
for Research in Computer Science and Control (INRIA) in France and
Keio University in Japan. Services provided
by the Consortium include: a repository of information about the World Wide
Web for developers and users, sample code implementations to embody and promote
standards, and various prototype and sample applications to demonstrate use
of new technology. To date, over 300 organizations are
Members of the Consortium.